leaving my 03 pathfinder in 4 wheel drive mode

[rhondas]

say is it OK to leave my 03 pathfinder in 4 wheel drive when I shut it off for the day

[04pathse]

It is just fine to do this.

[Rogue One]

Moved to Pathfinder forum.

[Hawairish]

Just curious, but does this mean you're needing 4wd to get to your overnight parking spot?

[Buzzman]

say is it OK to leave my 03 pathfinder in 4 wheel drive when I shut it off for the day

Do you drive it in 4WD all the time?

[yeldogt]

The pathfinder is an old school 4wd --- you should not be driving on clear pavement with the 4wd engaged.

It's not AWD

[vonscorpio]

Just curious, but does this mean you're needing 4wd to get to your overnight parking spot?

I was wondering the same thing...
My 01 QX4 has 2WD, AWD, 4WD and 4WD Low modes.

Perhaps he means AWD? If so, I have noticed when I drive in AWD, due to slick roads, when I park and shut off the engine, there is a definite shift from somewhere in the transmission/transfer case.

[Buzzman]

I have noticed when I drive in AWD, when I park and shut off the engine, there is a definite shift from somewhere in the transmission/transfer case.

This is normal.
It's even mentioned in the owners manual.

[yeldogt]

It is normal --

But if you read the manual you will see that the truck is not AWD -- you should stay under 50mph in 4WD.

The Path is old school -- the dif is locked. It's not designed to stay in 4WD on dry pavement. The front wheels don't turn independent ... the only slip is between the pavement and the tires ... not good.

Use the "auto" setting

[vonscorpio]

But if you read the manual you will see that the truck is not AWD

I confused the "AUTO" mode with "AWD."

Does AUTO function like real-time AWD?

I usually drive in 2WD mode anyway, but are you saying to stay under 50 MPH in AUTO mode? Or just the 4WD locked modes?

[yeldogt]

The truck does not have AWD.

The "Auto' position is like an "on" button ... like turning the Cruse Control "on" ... The CC is not operating until you set the speed.

Nissan gave the pathfinder an electric transfer case. Reason: The market was developing more advanced and easier to use 4WD systems back in the 90's --- having to stop and shift manually .. and then additionally have to manually shift into 'Low" made the Pathfinder unappealing to many buyers. Nissan used the ABS sensors and traction control system to monitor the rear wheels for slipping ... once detected ... it would engage the front wheels using the electric transfer case. The system does not keep the front wheels engaged -- the transfer case quickly goes back to 2WD.

If you drove a Pathfinder on dry pavement and never spun the rear wheels -- the 4WD system would never engage. Ever. It's a 2WD truck .. except for the short time it's switched over .... or the driver moves the knob to one of the two 4WD positions.

The other positions ( low/ high) are needed. Pulling a boat up a ramp needs 4WD low ... I use the 4WD high position to get out of my long driveway in the snow. I want the truck to stay in 4WD ... when the roads are snow covered I use 4WD high. I'm not sure why the 2WD position is called what it is ... it should be called "off" ... that's what it does . Stops the transfer case from operating.

SO ... in "auto" you can do whatever speed you want.

When it's in 4WD -- the front wheels are locked together. On a curve the inside wheel is turning (spinning) less -- so the two front wheels are not rotating at the same speed. Something has to give -- and it's the tires rubbing against the pavement.

AWD allows the wheels to turn at different speeds -- and be providing power. many different systems. Pathfinder does not have

True ... old style 4WD is simple, effective and robust ...

[Hawairish]

He could leave it in Auto if he has the all-mode system. But all it does is toggle between 2H, 4H, and 4L. But as such, auto does not function as AWD...it functions as a "smarter" part-time 4WD.

Typically in an AWD system, torque can be sent to any wheel at any given moment, and some systems can ration or lock the center diff to distribute power automatically to both front and rear axles in certain low-traction conditions. In ours, when 4wd is engaged, it always sends half the power to the front, and half to the rear. At times, an AWD system can resemble a 4wd system (i.e., with 50/50 locked center diff active), but a 4wd can't resemble an AWD system.

[vonscorpio]

Thanks for the explanation.

I've used the AUTO mode at freeway speeds once or twice in heavy rain and once I hit 55-60 MPH the backend started to wag like a dogs tail. Dropped back to 2WD and it drove like "normal"... Which to be fair, the bushings are out in the backend, and on a good day at freeway speeds I've got the "sway of death" to worry about.

Does AUTO mode noticeably reduce fuel economy?
And based on your explanation, am I correct in assuming I should only switch out of 2WD mode when I suspect I might need it?

[fastpakr]

You can put it into the Auto mode anytime you think you might need 4wd but don't want to be constantly switching in and out manually. If the system detects slip, it should lock in the transfer case to engage the front drive components. I'll switch to 4wd if I'm consistently in terrain that allows some natural slip (to release any driveline bind) like driving on snow. If it's intermittent, then I'll put it in the automatic mode instead.

When it's in 4WD -- the front wheels are locked together. On a curve the inside wheel is turning (spinning) less -- so the two front wheels are not rotating at the same speed. Something has to give -- and it's the tires rubbing against the pavement.

The front end is -NOT- locked together side to side in either 4wd mode. That would only take place if the differential was replaced with a spool or other fully locked unit. The bind comes from the front and rear drivelines being locked together, not left and right sides.

[yeldogt]

Read the manual on the front differential ... Tire wear etc..


Vonscorpio: The only way "auto" can reduce MPG is for it to be in 4WD -- and it's engaged for such a short time I can't see that effecting MPG's much.

I leave mine in "AUTO" ...........that's the point ... it gives you the extra traction when you need it.

I think something else is going on with your truck -- regarding the speed ,,,,, I bet the bushing need replacing and nothing to do with the front differential.

[vonscorpio]

I think something else is going on with your truck -- regarding the speed ,,,,, I bet the bushing need replacing and nothing to do with the front differential.

I have all the new bushings for the rear trailing arms-- Poly ones to boot! Just haven't gotten around to doing the work. Probably just going to hire my friend who has a lift in his garage to do the work.
Since I only commute to and from work on the infamous Bellevue, WA I-405, I never get over 40 MPH, let alone actual freeway speeds, I figure I'm fine for the next few hundred miles.

Thanks everyone for the education on my vehicle's drivetrain. I learned a lot!

I hope rhondas got their answer-- and doesn't mind that we kind of high-jacked the thread.

[fastpakr]

Read the manual on the front differential ... Tire wear etc..

Was that addressed to me?

[Hawairish]

When it's in 4WD -- the front wheels are locked together. On a curve the inside wheel is turning (spinning) less -- so the two front wheels are not rotating at the same speed. Something has to give -- and it's the tires rubbing against the pavement.

The front end is -NOT- locked together side to side in either 4wd mode. That would only take place if the differential was replaced with a spool or other fully locked unit. The bind comes from the front and rear drivelines being locked together, not left and right sides.

Fastpakr is correct on this.

[Hawairish]

I've used the AUTO mode at freeway speeds once or twice in heavy rain and once I hit 55-60 MPH the backend started to wag like a dogs tail. Dropped back to 2WD and it drove like "normal"... Which to be fair, the bushings are out in the backend, and on a good day at freeway speeds I've got the "sway of death" to worry about.

There shouldn't be a difference. The all-mode system wouldn't engage 4H on a wet road, especially at that speed.

[yeldogt]

Google ATTESA E-TS

The transfer case in the QX4's and the later LE Pathfinders is only operational in the "auto" position. You get no benefit from the system in 2WD. It has a multi clutch -- viscous coupling. That is why it needs auto trans fluid -- it has set points whereby it can vary the torque going to the front wheels -- up to 50%. It's a slick little setup .. and rather complicated.

In both of the 4WD modes -- it locks ... so you no longer get the ability to slip. The front Differential design in the Pathfinders is different -- the numbers are the same (R200A) as others in the Nissan line .... but the design of the gears are cut in reverse of the others. I forget now what it is called. They never made a limited slip for the front. The front differential is why they limit the 4WD H to 50pmh and you get the binding on dry pavement and in turns.

Nissan sold variations of the Pathfinder all over the world --- they developed the unit body so it could be lighter. The drivetrain was also used all over the world and in a ROW pickup truck. It had to be robust ... the US market demanded something different and they had to create this stop gap transfer case. I go to Africa often -- they are all over the place. If not for the rust they would run forever.

[Hawairish]

Ok...but it's not locking in the manner you described.

From the Wiki:

To control the ATTESA E-TS system, there is a 16-bit computer that monitors the cars movements 10 times per second to sense traction loss by measuring the speed of each wheel via the ABS sensors. Also a three-axis G-Sensor mounted underneath the center console feeds lateral and longitudinal inputs into a computer, which controls both the ATTESA-ETS 4WD system and the ABS system. The computer can then direct up to 50% of the power to the front wheels. When slip is detected on one of the rear wheels (a rear wheel turn 5% or more than the front wheels), the system directs torque to the front wheels which run a non-limited slip differential. Rather than locking the AWD in all the time or having a system that is "all or nothing", the ATTESA E-TS system can apportion different torque ratios to the front wheels as it sees fit. This provides the driver with an AWD vehicle that performs like a rear wheel drive vehicle in perfect conditions and can recover control when conditions aren't as perfect.

The take-away is it's able to send power to the front axle on demand (in AUTO mode only), and it uses a combination of transfer case engagement and individual wheel braking to restore traction. Aside from the use of a traditional t-case (which the QX4 uses because it supports 2H, 4H, and 4L modes), this is pretty much how all electronic traction control systems work: they ration braking.

Here, when a traction delta is detected (via ABS tone rings and g-sensors), the system sends power to the front and applies the brakes slightly to any wheel(s) with deviated traction relative to sensor data. This shifts power to the other wheels that "had" more traction (because now they will have less). Power always goes to the wheel with the least traction with an open diff, like a stock R200A. Though technically, this all essentially makes the QX4's all-mode system a "full-time 4wd" system, compared to the part-time 4wd systems found on all other R50s.

But there's nothing magical about all this...this concept is even an old off-roading trick where you apply the brake or e-brake just enough manipulate the power shift, in particular if you have a wheel off the ground. This "locks" up the up-wheel and sends power to the down-wheel, but this is only useful until the down-wheel resistance exceeds that of the braking resistance on the up-wheel.

But, under no circumstances is the system capable of locking the front diff, which I believe was your argument. (Do correct me if wrong.) The front differential has no impact on speed limits for the 4WD system, and it alone doesn't cause binding. It's a rather dumb axle. As Fastpakr stated previously, at any given time, at least 1 front and 1 rear tire are always spinning at the same speed when 4wd is engaged. When you turn, binding occurs because there's just enough rotational difference between 1 front tire and 1 rear tire, and not from 2 front tires (each outer tire per axle is free to rotate faster with an open diff). You can have additional binding if you have the front and/or rear differential mechanically locked. Auto-lockers (aka lunchbox lockers, or rather, "auto-unlockers") like Lokka, Spartan, Lock-Rite, and Detroit can disengage to allow the outer tire to overtake the inner tire...that's why you hear clicking around corners if you have those installed. An ARB or TJM air locker doesn't disengage around corners.

I'm no stranger to the R200A, btw...or the rear H233B for that matter. I have 3 spares of each in my garage right now, including a full H233B axle. I've installed Lokkas and re-packed LSDs, and even have an "extra" ARB on my workbench. I also have a full write-up of the differences between the R50 and non-R50 diffs on NPORA, in which I'm currently discussing how to make a non-R50 fit an R50, in case you're interested: http://www.nissanpathfinders.net/forum/ ... -the-diff/

That all said, I assure you the stock R200A is incapable of locking tires left-to-right without a mechanical locker (which I have), regardless of which Nissan 4WD system it has.

[fastpakr]

Yep, and just to add to that: Because the R50 doesn't have unlockable hubs, the front differential is always rotating regardless of the transfer case setting. It's just not bound to the rest of the driveline through the transfer case.

[Hawairish]

Yep, and just to add to that: Because the R50 doesn't have unlockable hubs, the front differential is always rotating regardless of the transfer case setting. It's just not bound to the rest of the driveline through the transfer case.

Good point, and maybe that's part of the confusion here. The wheel hubs are always "locked" to the differential, but that doesn't mean that the wheel hubs are locked to each other. That's what a mechanical locker does.

[yeldogt]

The Pathfinders and the QX4's ... don't have the capacity to modulate the ABS system in response to the 4WD. It uses the sensors on the rear wheel and the TPS. It also can't put the truck into 4H or L -- both of these lock the converter .. and that does not happen in "auto". The transfer case is unusual -- the rest of the system is not.

Correct -- the front is always rotating.

I'm speaking of when the transfer case is locked and under power.

[Hawairish]

Ok, but we've been talking about the Auto mode, not explicitly-switched 4H/4L, and the ABS system's involvement for that. It uses inputs from all wheels, as well as an speed sensor for the front driveshaft. It has to use input from all wheels, otherwise it couldn't detect when the rear wheels were slipping.

And actually, it can lock the vehicle in 4H or 4L if conditions permit (low speed, high rear wheel slip) but will only do so as long as conditions require. That's what the Auto is for, versus "locked" 4H/4L. It would be inefficient for it to rely solely on viscous pressure for a 4H situation when it could just lock the gear (which btw, according to the FSM, is the function of the Wait Detection Switch).

But look, let's take a step back: the initial challenge argument was about the front differential locking and the source of binding in 4WD (interpreted as 4H/4L). Why is the Auto mode functionality being use as a rebuttal here? Apples to oranges.

And when the t-case is locked, it doesn't matter if it's under power or not...it doesn't lock the front differential. It can't. Is that what you're debating?

[yeldogt]

The system has to have a delay in Auto mode -- otherwise it would be jumping in and out. The system can't go into low. To go into low the car can't be at speed. It has a reduction gear.

The system is inefficient. It needs the pump for low/no speed. I don't remember seeing any sensor on the front diff for speed rotation.

Believe I clarified the locking was the transfer case: When in -- 4H / 4L. I'm not talking about the front differential. I'm not talking about the front differential locking ... it's an old school differential. Having a LSD would have been interesting.

I'm talking about the basic binding that occurs in an old school 4WD system with the locked center differential. This is why Nissan recommends 50mph and no dry pavement -- and in turning situations the forces increase on the drivetrain.

It has rear drum brakes with a common circuit -- so the ABS is not the same as four wheel disk. It can't modulate the rears the same way.

People keep thinking that Auto is .. all wheel drive ... it's not. That's what this thread is all about ... explaining what is going on and why. Many true AWD systems don't lock the center diff. Some can -- like the Porsche and RR.

The Pathfinder does lock in 4H/4L ... and the OP should be using "Auto" ... and only using 4H or 4L when the conditions warrant .. and follow the owners manual.

[Hawairish]

Alright, well thanks for clarifying, sorta. Again, Fastpakr and I were hinging off your comment "the front wheels are locked together," which is wrong. I think the rest of the discussion just got muddled.

If you really want to look into it further, the FSM specs front and rear wheel speed signals on the transmission (rear) and t-case (front). (See TF-11 and TF-12 of the 2003 QX4 FSM). It also specs input from the ABS control unit, which might provide additional logic. Unfortunately, the TF section lacks a System Description that would have clarified all system criteria.

And although the rear drum brakes are physically plumbed together, each side has it's own tone ring (unlike some Xterras and Frontiers that had a shared ring on the diff), and the ABS system will modulate braking to the entire axle, and also the front wheels separately.

Some of my descriptions earlier were meant to be generic, but I can see that some of it may have been interpreted for QX4-specific. And yes, typo on my part about the 4L engagement...was getting carried away typing "4H/4L" together.

But look, I don't want to drone on about all this. The OP's never going to reply, and we can speculate what he's doing or not doing all day long. It really doesn't matter at this point, right?

[rhondas]

Just curious, but does this mean you're needing 4wd to get to your overnight parking spot?

yes a long upgrade driveway

[yeldogt]

I have a long driveway at my winter weekend place. I use 4WH when the drive is covered in heavy new snow ... I turn it back to "Auto" when I get to the house. I turn it back so it's not in 4WH for the next driver ... My clan never looks at the dash and would drive it in 4WD until the wheels fell off.

Hawairish: I may be wrong .. but I think the QX4 and the Pathfinder LE past 2002 have the same set up. Mine have all been 02 LE's -- so I'm only going by that configuration.

I'm not sure what I am going to do when this one has to go -- maybe I will get lucky and find another perfect one ... this is my third. I like that I have the locking center when I need it and have the "Auto" for the rest. I have a big property and the ground clearance and toughness of the Paths system is desirable over most of the AWD systems in all the crossovers.

[Hawairish]

Just curious, but does this mean you're needing 4wd to get to your overnight parking spot?

yes a long upgrade driveway

Not sure what the facepalm's about, but that doesn't give any indication that 4wd was required. Is it a long paved upgrade driveway covered in snow or dirt or rock or mud or kitty litter or crocodile tears? Are you parking on the upgrade, or is it leveled at the top where you park? I mean, parking on an upgrade that requires 4wd in the first place sounds like a pretty bad decision in general, but you weren't very clear. Myself and others were just checking if the use of 4wd, and leaving it engaged while parked, was warranted because the best answer to your question was dependent on such info.